Security latch for sashes

Abstract

A security latch for sashes comprises a shell body, a moving piece, an axle and a resilient assembly. An accommodating cavity is formed inside the shell body and opened at a flat side of the shell body, and a first concave surface is formed at a bottom of the accommodating cavity away from the flat side. The moving piece is received in the accommodating cavity and is rotatable around the axle installed in the accommodating cavity. The moving piece comprises an engaging face formed at a side thereof and a second concave surface formed at another side thereof. The resilient assembly is disposed between the first concave surface and the second concave surface to resiliently and movably engage with the first and second concave surfaces. The engaging face emerges out of the accommodating cavity from the flat side for blocking any movement along the flat side.

What is claimed is: 
     
         1 . A security latch for sashes, comprising:
 a shell body comprising a flat side, an accommodating cavity formed inside the shell body and opened at the flat side to communicate with an outside of the shell body, a first concave surface formed at a bottom of the accommodating cavity away from the flat side;   a moving piece received in the accommodating cavity and comprising an engaging face formed at a side of the moving piece, the moving piece capable of allowing the engaging face emerging out of the accommodating cavity from the flat side for blocking any movement along the flat side of the shell body, a second concave surface formed at another side of the moving piece to face toward the first concave surface of the shell body when the moving piece is received in the accommodating cavity;   an axle installed at the shell body to penetrate through the moving piece so as to allow the moving piece being movable and rotatable around the axle in the accommodating cavity, the moving piece rotating around the axle from a first position of the moving piece where the engaging face of the moving piece emerges outside the flat side of the shell body for blocking to a second position of the moving piece where the engaging face of the moving piece is retracted back in the accommodating cavity of the shell body; and   a resilient assembly comprising two seats each of which is disposed at one of two distal ends of the resilient assembly, the resilient assembly defining a virtual central longitudinal axis to respectively pass through the two seats, the resilient assembly disposed between the first concave surface of the shell body and the second concave surface of the moving piece to resiliently and movably engage with the first and second concave surfaces via the two seats of the resilient assembly, respectively, the longitudinal axis of the resilient assembly being collinear with a virtual line defined to be connected between an engaging point of one of the two seats and the first concave surface, and an engaging point of the other of the two seats and the second concave surface when the two seats of the resilient assembly respectively move along and engage with the first and second concave surfaces due to movement of the moving piece around the axle between the first and second positions thereof in the accommodating cavity of the shell body.   
     
     
         2 . The security latch for sashes as claimed in  claim 1 , wherein each of the two seats of the resilient assembly comprises a hemispherical head to move along and engage with a corresponding one of the first and second concave surfaces. 
     
     
         3 . The security latch for sashes as claimed in  claim 2 , wherein a spiral spring is disposed between the two seats of the resilient assembly, a pole extending from the head of the each of the two seats is inserted and restrainedly stays in an inner space of the spiral spring. 
     
     
         4 . The security latch for sashes as claimed in  claim 1 , wherein a stopper is formed at a side of the engaging face of the moving piece, and a step is formed at the bottom of the accommodating cavity next to the first concave surface, the stopper is engaged with the step to stop further movement of the moving piece when the moving piece moves from the first position thereof to the second position thereof and is located in the second position thereof. 
     
     
         5 . The security latch for sashes as claimed in  claim 4 , wherein the stopper moves to the flat side of the shell body, and a side of the stopper is flush with the flat face of the shell body and the stopper is entirely located in the accommodating cavity of the shell body when the moving piece moves from the second position thereof to the first position thereof and is located in the first position thereof. 
     
     
         6 . The security latch for sashes as claimed in  claim 1 , wherein a protrusion is formed at another side of the moving piece opposite to the engaging face, and a recess is formed at a corner of the bottom of the accommodating cavity different from the first concave surface, the protrusion is engaged with and stays in the recess to stop further movement of the moving piece when the moving piece moves from the second position thereof to the first position thereof and is located in the first position thereof. 
     
     
         7 . The security latch for sashes as claimed in  claim 1 , wherein a first arm and a second arm respectively extend from and along two opposite outer sides of the shell body, and are respectively spaced mostly from the outer sides of the shell body for installation of the security latch to a sash. 
     
     
         8 . A security latch for sashes, comprising:
 a shell body comprising a flat side, an accommodating cavity formed inside the shell body and opened at the flat side to communicate with an outside of the shell body, a first concave surface formed at a bottom of the accommodating cavity away from the flat side;   a moving piece received in the accommodating cavity, and being movable and rotatable around an axle installed at the shell body in the accommodating cavity, the moving piece comprising an engaging face formed at a side of the moving piece, the moving piece capable of allowing the engaging face emerging out of the accommodating cavity from the flat side for blocking any movement along the flat side of the shell body, a second concave surface formed at another side of the moving piece to face toward the first concave surface of the shell body when the moving piece is movably received in the accommodating cavity, the moving piece rotating around the axle from a first position of the moving piece where the engaging face of the moving piece emerges outside the flat side of the shell body for blocking to a second position of the moving piece where the engaging face of the moving piece is retracted back in the accommodating cavity of the shell body; and   a resilient assembly defining a virtual central longitudinal axis to extend along the resilient assembly, the resilient assembly disposed between the first concave surface of the shell body and the second concave surface of the moving piece to resiliently and movably engage with the first and second concave surfaces, respectively, the longitudinal axis of the resilient assembly being collinear with a virtual connecting line between a curvature center of the first concave surface of the shell body and a curvature center of the second concave surface of the moving piece when the resilient assembly respectively moves along and engages with the first and second concave surfaces due to movement of the moving piece around the axle between the first and second positions thereof in the accommodating cavity of the shell body.   
     
     
         9 . A security latch for sashes, comprising:
 a shell body comprising a flat side, an accommodating cavity formed inside the shell body and opened at the flat side to communicate with an outside of the shell body, a first concave surface formed at a bottom of the accommodating cavity away from the flat side;   a moving piece received in the accommodating cavity and comprising an engaging face formed at a side of the moving piece, the moving piece capable of allowing the engaging face emerging out of the accommodating cavity from the flat side for blocking any movement along the flat side of the shell body, a second concave surface formed at another side of the moving piece to face toward the first concave surface of the shell body when the moving piece is received in the accommodating cavity;   an axle installed at the shell body in the accommodating cavity so as to allow the moving piece being movable and rotatable around the axle in the accommodating cavity, the moving piece rotating around the axle from a first position of the moving piece where the engaging face of the moving piece emerges outside the flat side of the shell body for blocking to a second position of the moving piece where the engaging face of the moving piece is retracted back in the accommodating cavity of the shell body; and   a resilient assembly defining a virtual central longitudinal axis extending longitudinally through the resilient assembly, the resilient assembly disposed between the first concave surface of the shell body and the second concave surface of the moving piece to resiliently and movably engage with the first and second concave surfaces, respectively, wherein a third position of the moving piece is defined where the axle is located at a virtual extension line of the longitudinal axis of the resilient assembly, the resilient assembly generates a resistant spring force against an external force applied on the moving piece when the moving piece moves from the first position to the third position, or from the second position to the third position, and releases the resistant spring force to drive the moving piece moving when the moving piece rotates from the third position to either one of the first and second positions.   
     
     
         10 . The security latch for sashes as claimed in  claim 9 , wherein the resilient assembly comprises two seats, each of the two seats is disposed at one of two distal ends of the resilient assembly, and comprises a head to move along and engage with a corresponding one of the first and second concave surfaces. 
     
     
         11 . The security latch for sashes as claimed in  claim 10 , wherein a spiral spring is disposed between the two seats of the resilient assembly, a pole extending from the head of the each of the two seats is inserted and restrainedly stays in an inner space of the spiral spring. 
     
     
         12 . The security latch for sashes as claimed in  claim 9 , wherein a stopper is formed at a side of the engaging face of the moving piece, and a step is formed at the bottom of the accommodating cavity next to the first concave surface, the stopper is engaged with the step to stop further movement of the moving piece when the moving piece moves from the first position thereof to the second position thereof and is located in the second position thereof. 
     
     
         13 . The security latch for sashes as claimed in  claim 12 , wherein the stopper moves to the flat side of the shell body, and a side of the stopper is flush with the flat face of the shell body and the stopper is entirely located in the accommodating cavity of the shell body when the moving piece moves from the second position thereof to the first position thereof and is located in the first position thereof. 
     
     
         14 . The security latch for sashes as claimed in  claim 9 , wherein a protrusion is formed at another side of the moving piece opposite to the engaging face, and a recess is formed at a corner of the bottom of the accommodating cavity different from the first concave surface, the protrusion is engaged with and stays in the recess to stop further movement of the moving piece when the moving piece moves from the second position thereof to the first position thereof and is located in the first position thereof. 
     
     
         15 . The security latch for sashes as claimed in  claim 9 , wherein a first arm and a second arm respectively extend from and along two opposite outer sides of the shell body, and are respectively spaced mostly from the outer sides of the shell body for installation of the security latch to a sash. 
     
     
         16 . A security latch for sashes, comprising:
 a shell body comprising a flat side, an accommodating cavity formed inside the shell body and opened at the flat side to communicate with an outside of the shell body, a first concave surface formed at a bottom of the accommodating cavity away from the flat side;   a moving piece received in the accommodating cavity, and being movable and rotatable around an axle installed at the shell body in the accommodating cavity, the moving piece comprising an engaging face formed at a side of the moving piece, the moving piece capable of allowing the engaging face emerging out of the accommodating cavity from the flat side for blocking any movement along the flat side of the shell body, a second concave surface formed at another side of the moving piece to face toward the first concave surface of the shell body when the moving piece is movably received in the accommodating cavity, the moving piece rotating around the axle from a first position of the moving piece where the engaging face of the moving piece emerges outside the flat side of the shell body for blocking to a second position of the moving piece where the engaging face of the moving piece is retracted back in the accommodating cavity of the shell body; and   a resilient assembly disposed between the first concave surface of the shell body and the second concave surface of the moving piece to resiliently and movably engage with the first and second concave surfaces, respectively, the resilient assembly defining a virtual central longitudinal axis extending longitudinally through the resilient assembly, and comprising two seats each of which is disposed at one of two distal ends of the resilient assembly, wherein the each of the two seats maintains movement thereof along the longitudinal axis of the resilient assembly when the resilient assembly moves between the first concave surface of the shell body and the second concave surface of the moving piece due to rotation of the moving piece around the axle between the first and second positions of the moving piece.   
     
     
         17 . The security latch for sashes as claimed in  claim 16 , wherein a spiral spring is disposed between the two seats of the resilient assembly, the each of the two seats comprises a head to move along and engage with a corresponding one of the first and second concave surfaces, a pole extending from the head of the each of the two seats is inserted and restrainedly stays in an inner space of the spiral spring. 
     
     
         18 . The security latch for sashes as claimed in  claim 16 , wherein a stopper is formed at a side of the engaging face of the moving piece, and a step is formed at the bottom of the accommodating cavity next to the first concave surface, the stopper is engaged with the step to stop further movement of the moving piece when the moving piece moves from the first position thereof to the second position thereof and is located in the second position thereof. 
     
     
         19 . The security latch for sashes as claimed in  claim 16 , wherein a protrusion is formed at another side of the moving piece opposite to the engaging face, and a recess is formed at a corner of the bottom of the accommodating cavity different from the first concave surface, the protrusion is engaged with and stays in the recess to stop further movement of the moving piece when the moving piece moves from the second position thereof to the first position thereof and is located in the first position thereof. 
     
     
         20 . The security latch for sashes as claimed in  claim 16 , wherein a first arm and a second arm respectively extend from and along two opposite outer sides of the shell body, and are respectively spaced mostly from the outer sides of the shell body for installation of the security latch to a sash.